Cheer around circuit (4)
I believe the answer is:
clap
'cheer' is the definition.
(I've seen this before)
'around circuit' is the wordplay.
'around' becomes 'c' (abbreviation for 'circa').
'circuit' becomes 'lap' (synonyms).
'c'+'lap'='CLAP'
(Other definitions for clap that I've seen before include "express approval" , "Applaud manually" , "Express approbation with the hands" , "Make sound of applause" , "Pat" .)