One's hooked a roach: get excited reeling in biggun, finally (10)
I believe the answer is:
coathanger
'reeling in biggun finally' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'one's hooked a roach get excited' is the wordplay.
'one' becomes 'an' (an apple is one apple).
'hooked' indicates putting letters inside (inserted letters are hooked or caught inside).
'excited' indicates anagramming the letters.
'roach'+'get'='roachget'
'roachget' is an anagram of 'coathger'.
'an' going inside 'coathger' is 'COATHANGER'.
Can you help me to learn more?
(Another definition for coathanger that I've seen is " Curved piece of wood with a hook in a wardrobe".)