Johnny Morris finally to meet PM in 1971 (6)
I believe the answer is:
sheath
'johnny morris' is the definition.
The definition suggests a singular noun which matches the answer.
'finally to meet pm in 1971' is the wordplay.
I cannot quite see how this works, but
'pm' could be 'heath' (I've seen this before) and 'heath' is found in the answer.
A single letter 's' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sheath that I've seen before include "coat" , "Blade-cover" , "Casing for a sword" , "Cover for a blade" , "Protective covering for a knife" .)