What Haughey's sensing when Mara says 'no more nibbling at my leader's bum' - we're going through austerity (7,3,5)
I believe the answer is:
feeling the pinch
Here is my best explanation:
'more nibbling at my leader's bum we're going through austerity' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'what haughey's sensing when mara says no' is the wordplay.
I cannot quite understand how this works, but
'sensing' could be 'feeling' ('feel' can be a synonym of 'sense') and 'feeling' is located in the answer.
'when' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'no' could be 'n' (common abbreviation) and 'n' is found in the answer.
This explanation may well be incorrect...
(Other definitions for feeling the pinch that I've seen before include "having a lack of finance" and "Getting arrested".)