Only odd anglers needed a long time (4)
I believe the answer is:
ages
'a long time' is the definition.
(ages can mean a very long time)
'only odd anglers' is the wordplay.
'only odd' indicates alternate letters.
The alternate letters of 'anglers' are 'AGES'.
'needed' is the link.
(Other definitions for ages that I've seen before include "Yonks" , "Matures" , "Epochs" , "Times" , "Historical eras" .)