The kind of varnish for a spar or pole, I see (6)
I believe the answer is:
mastic
'the kind of varnish for a spar' is the definition.
I can't judge whether this defines the answer.
'pole i see' is the wordplay.
'pole' becomes 'mast' (mast is a kind of pole).
'see' becomes 'C' (the word for the letter, according to Chambers).
'mast'+'i'+'c'='MASTIC'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for mastic that I've seen before include "Aromatic resin used to make varnish" , "Putty-like cement used as adhesive or filler" , "Resin used in varnishes" , "Gum from trees" , "Waterproof sealant" .)