So in love with dominant rotter? (4,4,5)
I believe the answer is:
head over heels
'so in love' is the definition.
(informal phrase meaning very much in love)
'dominant rotter?' is the wordplay.
I cannot really understand how this works, but
'rotter?' could be 'heel' (I've seen this in another clue) and 'heel' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'with' is the link.
Can you help me to learn more?
(Other definitions for head over heels that I've seen before include "(In relation to love) madly" , "In disorderly haste" , "topsy-turvy" , "Tumbling posture" , "Completely - turning as in a somersault" .)