Trade unions less organised for fights (7)
I believe the answer is:
tussles
'fights' is the definition.
(tussling is a kind of fighting)
'trade unions less organised' is the wordplay.
'trade unions' becomes 'TUs' (abbreviation).
'organised' indicates an anagram.
'less' anagrammed gives 'sles'.
'tus'+'sles'='TUSSLES'
'for' acts as a link.
(Other definitions for tussles that I've seen before include "Scraps" , "Struggles" , "Scuffles, dogfights" .)