Musically, "Clumsy" portrays a "synth-laden" electro song which incorporates doo-wop hand claps, stomping drums, finger snaps, soulful vocal riffs and an electronic drop in its instrumentation.
"Clumsy" was written by Talay Riley, Warren "Oak" Felder and Alex Niceforo, with production being handled by the latter two; Mischke Butler served as a vocal producer.
"[16] It additionally incorporates "stomping drums and finger snaps" in its instrumentation, as well as doo-wop "hand-claps and soulful vocal riffs as it builds to an explosive electronic drop.
"[19] Joey Nolfi, writing for Entertainment Weekly, saw "Clumsy" as being " sonically in-line with songs heard on 2011's Femme Fatale and 2013's Britney Jean.
"[18] Writing for Bustle, Alexis Rhiannon noticed that the text of the recording is "frankly pretty filthy" and "also essentially a description of pure sex.
"[17] Stephen Thomas Erlewine, writing for AllMusic, declared that "some of the highlights [on the album] are the silliest songs", citing "Clumsy" as an example and defining it as a "swinging" track.
[28] Neil McCormick of The Telegraph classified the track as "equating clumsiness with bumping and grinding sex," where "[Spears] switches back and forth between the two approaches so frequently that it almost sound like a duet between sweet and tough alter egos.
"[29] The National's Si Hawkins confessed that "Clumsy" is "a return to quirky form,"[30] while John Murphy of musicOMH emphasized that the song was an "undoubted highlight".
"[32] While noting that "Britney holds her own on the sexually charged 'Clumsy'," Sal Cinquemani of Slant Magazine suggested that Christina Aguilera would match better with the recording.
"[34] Alex Macpherson of The Guardian was largely positive towards "Clumsy", mentioning that it "brings out grinding, Justice-style metallic synths, verses that jitter and hop uncontrollably, beery chants and an absurd moment when Spears' voice gets pitch-shifted thither and yon.
But if much of her post-Blackout work seems to have had an absence of character as its end goal, [...] Spears sounds like she’s having the time of her life sparring with and riding the kitchen-sink beat.
He went on to say that "no singer [had] ever brought that much resonance to the word "oops"" referring to the song's lyrics and considered Britney a "TRL princess turned Vegas queen [who was revisiting] the high-energy disco-ball hysteria of her youth".