Over an ordeal about love, happy one is combative (12)
I believe the answer is:
gladiatorial
'combative' is the definition.
Although both the answer and definition are adjectives, I cannot see how one could define the other.
'over an ordeal about love happy one' is the wordplay.
I cannot quite understand how this works, but
'over' could be 'o' (cricket abbreviation) and 'o' is found in the answer.
'an' could be 'i' (Roman numeral for one) and 'i' is located in the answer.
'ordeal' could be 'trial' (I've seen this before) and 'trial' is present in the remaining letters.
'about' could be 'a' (abbreviation in Chambers) and 'a' is located in the answer.
'one' could be 'a' (a thing is one thing) and 'a' is present in the answer.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for gladiatorial that I've seen before include "Of combat in an arena" , "Of ancient Roman combat" , "featuring violent opponents" .)