Soldiers having miserable time in retreat (5)
I believe the answer is:
troop
'soldiers' is the definition.
(thesaurus)
'miserable time in retreat' is the wordplay.
'miserable' becomes 'poor' (synonyms).
'time' becomes 't' (abbreviation).
'in retreat' is a reversal indicator.
'poor'+'t'='poort'
'poort' backwards is 'TROOP'.
'having' is the link.
(Other definitions for troop that I've seen before include "Military unit" , "Body of soldiery" , "Flock; Scout group" , "Band of people" , "Group of kangaroos" .)