Finally improve, or go round the bend? (4,3,6)
I believe the answer is:
turn the corner
'finally improve' is the definition.
(eg when recovering from an illness)
'go round the bend?' is the wordplay.
'go round' becomes 'turn' ().
'bend?' becomes 'corner' (I've seen this before).
'turn'+'the'+'corner'='TURN THE CORNER'
'or' acts as a link.
(Other definitions for turn the corner that I've seen before include "Begin to get better" , "Start to improve" , "Get past the worst" , "Pass a critical point and improve" , "What driver at T-junction might do next" .)