Facing a dilemma when Celtic fan's kit is ruined (2,1,5,5)
I believe the answer is:
in a cleft stick
'facing a dilemma' is the definition.
(to be in a cleft stick is to face a dilemma)
'celtic fan's kit is ruined' is the wordplay.
'is ruined' indicates an anagram.
'celtic'+'fans'+'kit'='celticfanskit'
'celticfanskit' is an anagram of 'IN A CLEFT STICK'.
'when' is the link.
(Other definitions for in a cleft stick that I've seen before include "Within a difficult situation or dilemma" , "Between a rock and a hard place" .)