Keep crossing river to acquire new skills (7)
I believe the answer is:
retrain
'acquire new skills' is the definition.
(I've seen this before)
'keep crossing river' is the wordplay.
'keep' becomes 'retain' (retaining is a kind of keeping).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'river' becomes 'r' (abbreviation).
'retain' enclosing 'r' is 'RETRAIN'.
'to' acts as a link.
(Other definitions for retrain that I've seen before include "Gain new skills" , "Learn new skills" , "Terrain (anag.)" , "Teach (someone) new skills" , "coach yet again" .)