Worker supporting planet adopting line for fen country (9)
I believe the answer is:
marshland
'fen country' is the definition.
The definition suggests a singular noun which matches the answer.
'worker supporting planet adopting line' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'planet' becomes 'mars' (Mars is a planet).
'adopting' indicates putting letters inside (inserted letters are taken on or adopted).
'line' becomes 'l' (used when specifying particular lines from a poem).
'hand' after 'mars' is 'marshand'.
'marshand' enclosing 'l' is 'MARSHLAND'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for marshland that I've seen before include "Boggy territory" , "Boggy terrain" , "Boggy area" , "damp patch" , "Waterlogged area" .)