[3] He worked as an environmental management lecturer at Unitec Institute of Technology in Auckland and as a sustainable business advisor.

Along with MP Nándor Tánczos, former MP Mike Ward and 2005 election campaign manager Russel Norman, Clendon contested the Green's male leadership role in 2005 after the unexpected death of co-leader Rod Donald, saying that it made sense to "appoint an out-of-Parliament leader, rather than stretch the sitting MPs even further.

Green MP Sue Bradford resigned her seat in Parliament after she lost the party's co-leadership election to Metiria Turei in 2009.

[18] In the 2011 election, Clendon unsuccessfully contested the Mount Albert electorate but was re-elected as a list MP, ranked eighth.

[28][29] Graham and Clendon stated that their resignations were due to the public positions she had taken regarding her offending, and her subsequent refusal to step down from her leadership role.

Far North district councillor Willow-Jean Prime resigned her position in September 2017 after being elected to Parliament as a Labour list MP.

Clendon unsuccessfully contested the vacancy in a 2018 by-election,[6] but was successful in seeking a councillor role in the council's Bay of Islands–Whangaroa ward at the 2019 local elections.

[35] Prior to his election, Clendon was chair of Vision Kerikeri, a community development organisation and lobby group, from 2018 to 2019.

[39][40] He retired in 2022 after completing one term[41] and took a position as regional coordinator for the Tohu Whenua visitor programme in February 2024.