Very keen to be on the arm of an astronaut (6)
I believe the answer is:
strong
'very keen' is the definition.
'strong' can be an answer for 'keen' (thesaurus). I am not sure about the 'very' bit.
'on the arm of an astronaut' is the wordplay.
I cannot really understand how this works, but
'on' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for strong that I've seen before include "Intense" , "Resilient" , "Not easily broken" , "Great in power" , "Mighty, powerful" .)