Writers have a small room with a key on board (7)
I believe the answer is:
scribes
'writers' is the definition.
(scribe is a kind of writer)
'a small room with a key on board' is the wordplay.
'a small' becomes 's' (abbreviation - e.g. clothes size).
'room with' becomes 'cries' (I can't explain this - if you can you should give a lot more credence to this answer).
'a key' becomes 'b' (eg B major, musical key).
'on board' is an insertion indicator (inserted letters are taken on board).
'cries' going around 'b' is 'cribes'.
's'+'cribes'='SCRIBES'
'have' acts as a link.
Can you help me to learn more?
(Other definitions for scribes that I've seen before include "Ancient writers (7)" , "Copyists" , "People who once made hand-written copies" , "journos" .)