Old writer’s son leaving the navy with little speech (8)
I believe the answer is:
taciturn
'old' is the definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I can't see?
'writer's son leaving the navy with little speech' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'navy' could be 'rn' (abbreviation for Royal Navy) and 'rn' is found within the answer.
'writer' could be 'i' (the person who is writing these clues) and 'i' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for taciturn that I've seen before include "Habitually uncommunicative, saying little" , "Untalkative" , "Without saying much" , "Quiet and uncommunicative" , "Reserved, saying little" .)