Speak to a habit of speech (7)
I believe the answer is:
address
'speech' is the definition.
(synonyms)
'speak to a habit' is the wordplay.
'speak to' becomes 'ad' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a habit' becomes 'dress' (I've seen this in another clue).
'ad'+'dress'='ADDRESS'
'of' is the link.
Can you help me to learn more?
(Other definitions for address that I've seen before include "Place where someone lives" , "Place of abode" , "Attend" , "Speak to - direct" , "skilfulness or tact" .)