Crossword Genius

Mistreated a pony -- girth is shrinking (10)

Ross

I believe the answer is:

atrophying

'shrinking' is the definition.
(atrophying is a kind of shrinking)

'mistreated a pony girth' is the wordplay.
'mistreated' indicates anagramming the letters.
'a'+'pony'+'girth'='aponygirth'
'aponygirth' with letters rearranged gives 'ATROPHYING'.

'is' is the link.

I've seen this clue in The Telegraph.
Want a hint initially instead of a full solution? Install my app