Old lover on horrible trip had to pull up (9)
I believe the answer is:
extirpate
'pull up' is the definition.
(synonyms)
'old lover on horrible trip had' is the wordplay.
'old lover' becomes 'ex' (an ex-lover).
'on' is an insertion indicator.
'horrible' indicates anagramming the letters.
'had' becomes 'ate' ('have' can mean 'eat').
'trip' with letters rearranged gives 'tirp'.
'ex' inserted within 'tirp' is 'extirp'.
'extirp'+'ate'='EXTIRPATE'
'to' acts as a link.
(Other definitions for extirpate that I've seen before include "Root out" , "destroy utterly" , "Completely destroy" , "Remove completely" , "Destroy totally" .)