Free up relative nearly sitting on snake (7)
I believe the answer is:
unclasp
'free up' is the definition.
'unclasp' can be an answer for 'free' (thesaurus). I'm not sure about the 'up' bit.
'relative nearly sitting on snake' is the wordplay.
'relative' becomes 'uncle' (uncle is a kind of relative).
'nearly' means to remove the last letter.
'sitting on snake' becomes 'asp' (I can't justify this - if you can you should give a lot more credence to this answer).
'uncle' with its last letter removed is 'uncl'.
'uncl'+'asp'='UNCLASP'
Can you help me to learn more?
(Other definitions for unclasp that I've seen before include "Loosen grip on" , "let go" , "Open - release from grip" , "Unfasten" , "Detach (necklace, belt, etc)" .)