Female modifies flags (7)
I believe the answer is:
falters
'flags' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'female modifies' is the wordplay.
'female' becomes 'f' (common abbreviation).
'modifies' becomes 'alters' (I've seen this in another clue).
'f'+'alters'='FALTERS'
Can you help me to learn more?
(Other definitions for falters that I've seen before include "Stumbles, hesitates" , "Moves unsteadily, stumbles" , "'Loses confidence, begins to fail (7)'" .)