Pity it is that onions are such a nuisance to peel (6,5)
I believe the answer is:
crying shame
'that onions are such a nuisance to peel' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'pity it' is the wordplay.
I cannot quite see how this works, but
'pity' could be 'shame' (synonyms) and 'shame' is found in the answer.
The remaining letters 'crying' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Another definition for crying shame that I've seen is " Highly regrettable event".)