Entertain male teacher, one looking after the port (7,6)
I believe the answer is:
harbour master
'one looking after the port' is the definition.
The definition suggests a singular noun which matches the answer.
'entertain male teacher' is the wordplay.
'entertain' becomes 'harbour' (synonyms).
'male teacher' becomes 'master' (I've seen this before. I am not sure about the 'male' bit.).
'harbour'+'master'='HARBOUR-MASTER'
Can you help me to learn more?
(Other definitions for harbour master that I've seen before include "Person in charge of anchorage" , "Official supervising a port" , "Officer in charge of port" , "Port Authority" , "Port supervisor" .)