Reversed tactic of having defender as striker (4,2,5)
I believe the answer is:
back to front
'reversed' is the definition.
(thesaurus)
'tactic of having defender as striker' is the wordplay.
I cannot really see how this works, but
'of' could be 'o' and 'o' is found within the answer.
'defender' could be 'back' (left-backs and right-backs are football defenders) and 'back' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for back to front that I've seen before include "In reverse" , "At end of leave, soldiers' orders" , "This order's wrong" , "rejoin colleagues in the trenches?" , "Given wrong order" .)