Abandon crew's first couple in sub (5)
I believe the answer is:
scrub
'abandon' is the definition.
(scrub can mean to remove or delete)
'crew's first couple in sub' is the wordplay.
'crew's first' becomes 'c' (rst letter of 'crew').
'couple' becomes 'r' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'c'+'r'='cr'
'cr' inserted into 'sub' is 'SCRUB'.
Can you help me to learn more?
(Other definitions for scrub that I've seen before include "Wash the stunted shrub?" , "Rub hard - low vegetation" , "Brush dirt off - delete - stunted vegetation" , "Clean with hard brush and soapy water" , "Rub hard with a brush" .)