Good saving returns generating interest (4)
I believe the answer is:
grab
'interest' is the definition.
(I know that grab is a more specific form of the action fascinate)
'good saving returns' is the wordplay.
'good' becomes 'g' (abbreviation).
'saving' becomes 'bar' (I've seen this before).
'returns' is a reversal indicator.
'bar' back-to-front is 'rab'.
'g'+'rab'='GRAB'
'generating' acts as a link.
(Other definitions for grab that I've seen before include "Catch hold (of)" , "interest" , "Seize hold of" , "Seize roughly" , "Grasp roughly" .)