Tailor takes a day with fitting (5)
I believe the answer is:
adapt
'tailor' is the definition.
(I've seen this before)
'a day with fitting' is the wordplay.
'day' becomes 'd' (abbreviation for day).
'with' is a charade indicator (letters next to each other).
'fitting' becomes 'apt' (I've seen this before).
'a'+'d'+'apt'='ADAPT'
'takes' is the link.
(Other definitions for adapt that I've seen before include "Alter, amend" , "Change to suit a new purpose" , "get used?" , "Change to suit a different purpose" , "Modify, adjust" .)