Alkaline solution in something covered with glue - resin (9)
I believe the answer is:
polyester
'resin' is the definition.
(I know that polyester is a type of synthetic resin)
'alkaline solution in something covered with glue' is the wordplay.
'alkaline solution' becomes 'lye' (I've seen this in another clue).
'in' indicates putting letters inside.
'something' becomes 'er' (I've seen this in other clues).
'covered with' says to put letters next to each other (in a down clue, some letters go on top of others).
'glue' becomes 'post' (I can't explain this - if you can you should believe this answer much more).
'er' put after 'post' is 'poster'.
'lye' put within 'poster' is 'POLYESTER'.
Can you help me to learn more?
(Other definitions for polyester that I've seen before include "Stole prey (anag) - synthetic material" , "Synthetic textile" , "Turn to Presley for the synthetic fabric" , "Synthetic fibre or substance" , "This material goes out to Presley" .)