Loose favourite -- French one comes first (6)
I believe the answer is:
unpick
'loose' is the definition.
(unpick can mean to loosen)
'favourite french one comes first' is the wordplay.
'favourite french' becomes 'pick' (I can't justify this - if you can you should give a lot more credence to this answer).
'one' becomes 'un' (northern English dialect form of 'one').
'comes first' says to put letters next to each other.
'pick' put after 'un' is 'UNPICK'.
Can you help me to learn more?
(Other definitions for unpick that I've seen before include "subject to close scrutiny" , "analyse meticulously" , "Undo (stitches)" .)