Lent a hand when changing sides takes time (8)
I believe the answer is:
assisted
'lent a hand' is the definition.
(I've seen this before)
'when changing sides takes time' is the wordplay.
'when' becomes 'as'.
'changing' indicates anagramming the letters.
'takes time' becomes 't' (I've seen this in other clues).
'sides'+'t'='sidest'
'sidest' with letters rearranged gives 'sisted'.
'as'+'sisted'='ASSISTED'
(Other definitions for assisted that I've seen before include "Lent a hand" , "given help" , "to small sibling involved in stormy dates" , "Aided" , "Helped" .)