Who cares if pig has covering for head? (2,4)
I believe the answer is:
so what
'who cares' is the definition.
(I've seen this before)
'pig has covering for head?' is the wordplay.
I cannot really see how this works, but
'pig' could be 'sow' (I've seen this before) and 'sow' is found in the answer.
'covering' could be 'hat' (hat is a kind of covering) and 'hat' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'if' is the link.
Can you help me to learn more?
(Other definitions for so what that I've seen before include "It's unimportant, who cares" , "is that surprising?" , "Expresses contempt or lack of interest" , "Big deal!" , "Does it make any difference" .)