Tiger perhaps a bit upset about getting caught, initially (3,3)
I believe the answer is:
'tiger perhaps' is the definition.
(tiger is a kind of big cat)
'a bit upset about getting caught initially' is the wordplay.
'upset' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'initially' suggests taking the first letters.
The initial letters of 'getting caught' is 'gc'.
'abit' with letters rearranged gives 'biat'.
'biat' placed around 'gc' is 'BIG CAT'.
(Other definitions for big cat that I've seen before include "'Tiger or lion (3,3)'", "Lion or tiger, say", "One may have pride", "ounce, say", "Any large wild feline, like tiger or cheetah".)