Hook, for one, loses right to go after old partner to make amends (7)
I believe the answer is:
expiate
'to make amends' is the definition.
(I've seen this before)
'hook for one loses right to go after old partner' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'old' could be 'ex' and 'ex' is located in the answer.
'partner' could be 'e' and 'e' is present in the answer.
The remaining letters 'pat' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for expiate that I've seen before include "Make reparation" , "Atone for (guilt or wrongdoing)" , "Pay for" , "Of sin, make amends for" , "right?" .)