Gather there's action starting in valley (5)
I believe the answer is:
glean
'gather' is the definition.
(I've seen this before)
'action starting in valley' is the wordplay.
'starting' indicates taking the first letters.
'in' is an insertion indicator.
'valley' becomes 'glen' (glen is a kind of valley**).
The first letter of 'action' is 'a'.
'a' going into 'glen' is 'GLEAN'.
'there's' is the link.
(Other definitions for glean that I've seen before include "Collect bit by bit, often with difficulty" , "Gradually put together" , "Collect gradually (from various sources)" , "Gather, pick up" , "Collect small pieces" .)