Nick welcomes stranger addled by age (9)
I believe the answer is:
doddering
'addled by age' is the definition.
The answer and definition are not the same part of speech. However, adjectives and past participle verbs can sometimes define each other.
'nick welcomes stranger' is the wordplay.
'nick' becomes 'ding' (I've seen this in another clue).
'welcomes' indicates putting letters inside (in sense of 'invites in').
'stranger' becomes 'odder' (more odd).
'ding' going around 'odder' is 'DODDERING'.
Can you help me to learn more?
(Other definitions for doddering that I've seen before include "Feeble" , "shaking" , "Staggering" .)