Put a foot wrong doing right about turn (3)
I believe the answer is:
'put a foot wrong doing' is the definition.
I can't judge whether this definition defines the answer.
'right about turn' is the wordplay.
'right' becomes 'r' (common abbreviation).
'about' becomes 're' ('re' means regarding or about).
'turn' shows that the letters should be reversed in order.
'rre' back-to-front is 'ERR'.
Can you help me to learn more?
(Other definitions for err that I've seen before include "Miscalculate" , "Be mistaken" , "have an affair?" , "Stray from the straight and narrow" , "Make mistake in Canberra" .)