Was inclined to take a spare shirt! (5)
I believe the answer is:
leant
'was inclined' is the definition.
(I've seen this before)
'a spare shirt' is the wordplay.
'a spare' becomes 'lean' (I've seen this before).
'shirt' becomes 't' (as in a T-shirt).
'lean'+'t'='LEANT'
'to take' is the link.
(Other definitions for leant that I've seen before include "Inclined (towards)" , "Tipped" , "Tilted" , "Advanced" , "bent over" .)