Get back in gear after changing (6)
I believe the answer is:
regain
'get back' is the definition.
(I've seen this before)
'in gear after changing' is the wordplay.
'after' is a charade indicator (letters next to each other).
'changing' indicates an anagram.
'in'+'gear'='ingear'
'ingear' anagrammed gives 'REGAIN'.
(Other definitions for regain that I've seen before include "Recover, retrieve" , "Take back (the Ashes, for example)" , "Win back" , "Get back, recover the use of" , "Recover - in gear (anag)" .)