I do a turn, being funny for a time (8)
I believe the answer is:
duration
'a time' is the definition.
(duration is a kind of time)
'i do a turn being funny' is the wordplay.
'being funny' indicates anagramming the letters.
'i'+'do'+'a'+'turn'='idoaturn'
'idoaturn' with letters rearranged gives 'DURATION'.
'for' is the link.
(Other definitions for duration that I've seen before include "Period during which something continues" , "Around it (anag.)" , "Length of time" , "Time scale" , "Term, span, time" .)