With a bit of luck hitherto, we won't easily concede (5,2,3,5)
I believe the answer is:
throw in the towel
'concede' is the definition.
The definition and answer can be both related to competing as well as being verbs in their base form.
Perhaps you can see an association between them that I can't see?
'with a bit of luck hitherto we won't easily' is the wordplay.
'with' means one lot of letters go next to another.
'a bit of' indicates taking the first letters.
'easily' is an anagram indicator.
The initial letter of 'luck' is 'l'.
'l'+'hitherto'+'we'='lhithertowe'
'lhithertowe'+'wont' is 'lhithertowewont'.
'lhithertowewont' is an anagram of 'THROW IN THE TOWEL'.
Can you help me to learn more?
(Other definitions for throw in the towel that I've seen before include "Give oneself up" , "damp condition suggests one might?" , "Give up a venture" , "admit defeat" , "surrender after trading blows?" .)