Doctor Henry has a gin and large port (8)
I believe the answer is:
shanghai
'large port' is the definition.
'shanghai' can be an answer for 'port' (I've seen this before). I am not sure about the 'large' bit.
'doctor henry has a gin' is the wordplay.
'doctor' indicates an anagram.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'h'+'has'+'a'+'gin'='hhasagin'
'hhasagin' is an anagram of 'SHANGHAI'.
'and' is the link.
Can you help me to learn more?
(Other definitions for shanghai that I've seen before include "Darts player might be pleased with this" , "Once impressive" , "'What shall we do with a drunken sailor?'" , "Trick (someone) into becoming a sailor" , "Abduct to serve as a sailor" .)