Turning fat, short skinny monkey (6)

I believe the answer is:

gibbon

I'm a little stuck... Click here to teach me more about this clue!

'monkey' is the definition.
(I've seen this before)

'turning fat short skinny' is the wordplay.
'turning fat' becomes 'gib' (I can't explain this - if you can you should give a lot more credence to this answer).
'short' means to remove the last letter.
'skinny' becomes 'bony' (I've seen this in another clue).
'bony' with its final letter removed is 'bon'.
'gib'+'bon'='GIBBON'

Can you help me to learn more?

(Other definitions for gibbon that I've seen before include "Long-armed ape" , "author of Decline and Fall, etc" , "Type of ape" , "Large tailless ape" , "Small tree-dwelling ape with long powerful arms" .)

I've seen this clue in The Times.

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