Suffering, dad and I go in the pub (2,4)
I believe the answer is:
in pain
'suffering' is the definition.
(I've seen this before)
'dad and i go in the pub' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'and' says to put letters next to each other.
'go in' is an insertion indicator.
'the pub' becomes 'inn' (an inn is a type of pub).
'pa'+'i'='pai'
'pai' going within 'inn' is 'IN PAIN'.
(Other definitions for in pain that I've seen before include "Hurting" , "Suffering" .)