Corporation's uncontrolled urge to enter speculation (4,3)
I believe the answer is:
beer gut
'corporation's' is the definition.
(I have seen 'large corporation' mean 'beer gut' so perhaps 'corporation' could also mean 'beer gut')
'uncontrolled urge to enter speculation' is the wordplay.
'uncontrolled' is an anagram indicator.
'to enter' means one lot of letters goes inside another.
'speculation' becomes 'bet' (bet is a kind of speculation).
'urge' is an anagram of 'ergu'.
'ergu' inserted within 'bet' is 'BEER GUT'.
(Another definition for beer gut that I've seen is " large corporation".)