One fighting behind the lines cycling in ditch (7)
I believe the answer is:
chindit
'one fighting behind the lines' is the definition.
The definition suggests a singular noun which matches the answer.
'cycling in ditch' is the wordplay.
'cycling' indicates anagramming the letters.
'in'+'ditch'='inditch'
'inditch' is an anagram of 'CHINDIT'.
Can you help me to learn more?
(Other definitions for chindit that I've seen before include "WW2 allied commando in Burma" , "Burmese fighter" , "WW2 soldier" , "Old fighter in Burma" .)