Offer by regular tipster to soften things up (9)
I believe the answer is:
tenderise
'soften things up' is the definition.
(to tenderise is to soften)
'offer by regular tipster' is the wordplay.
'offer' becomes 'tender' (tender can mean to offer something).
'by' means one lot of letters go next to another.
'regular' indicates alternate letters.
The alternating letters of 'tipster' are 'ise'.
'tender'+'ise'='TENDERISE'
'to' acts as a link.
(Other definitions for tenderise that I've seen before include "pound" , "soften flesh" .)