After funny turn, energy to support pet cut short (8)
I believe the answer is:
truncate
'cut short' is the definition.
('truncate' can be a synonym of 'cut short')
'after funny turn energy to support pet' is the wordplay.
'after' says to put letters next to each other.
'funny' indicates anagramming the letters.
'energy' becomes 'e' (physics symbol as in E=mca).
'to support' is a charade indicator (letters next to each other) (in a down clue, some letters hold others up).
'pet' becomes 'cat' (I have seen 'Common pet ' mean 'cat' so perhaps 'pet' could also mean 'cat'**).
'turn' is an anagram of 'trun'.
'e' put after 'cat' is 'cate'.
'trun'+'cate' is 'TRUNCATE'.
(Other definitions for truncate that I've seen before include "Cut short" , "Dock" , "Shorten by cutting off the top" , "Lop" , "Make shorter by cutting off" .)