Attack from south-east with no place to retreat (3,4)
I believe the answer is:
set upon
'attack' is the definition.
(I know that set upon is a more specific form of the action attack)
'south-east with no place to retreat' is the wordplay.
'south east' becomes 'SE' (abbreviation).
'with' means one lot of letters go next to another.
'place' becomes 'put' (synonyms).
'to retreat' shows that the letters should be reversed in order.
'no'+'put'='noput'
'noput' back-to-front is 'tupon'.
'se'+'tupon'='SET UPON'
'from' is the link.
(Other definitions for set upon that I've seen before include "Attack" , "Mug" , "Attacked" , "Determined to do (something)" .)