Keep on manoeuvring, once one has backed in (8)
I believe the answer is:
continue
'keep on' is the definition.
(synonyms)
'manoeuvring once one has backed in' is the wordplay.
'manoeuvring' is an anagram indicator.
'one has' becomes 'unit' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'backed' says the letters should be written in reverse.
'in' is an insertion indicator.
'unit' back-to-front is 'tinu'.
'once' with letters rearranged gives 'cone'.
'cone' going around 'tinu' is 'CONTINUE'.
Can you help me to learn more?
(Other definitions for continue that I've seen before include "Proceed" , "Persist" , "Go on without stopping" , "Don't stop, keep going" , "Last" .)