Players crossing line move cautiously (5)
I believe the answer is:
sidle
'move cautiously' is the definition.
(I've seen this in another clue)
'players crossing line' is the wordplay.
'players' becomes 'side' (eg a football side).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'line' becomes 'l' (used when specifying particular lines from a poem).
'side' enclosing 'l' is 'SIDLE'.
(Other definitions for sidle that I've seen before include "Slink, creep, sneak" , "Make cautious progress" , "'Move sideways, furtively perhaps (5)'" , "Edge along laterally" , "Walk sideways in furtive manner" .)