Dreadful Ms Baker joins ship (7)
I believe the answer is:
embarks
'joins ship' is the definition.
The answer and definition can be both to do with social activities as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
'dreadful ms baker' is the wordplay.
'dreadful' indicates an anagram.
'ms'+'baker'='msbaker'
'msbaker' anagrammed gives 'EMBARKS'.
Can you help me to learn more?
(Other definitions for embarks that I've seen before include "Goes on board ship or plane" , "Sets out" , "Boards ship" , "Goes aboard" .)