Resemblance of lithium developed inside without hydrogen (10)
I believe the answer is:
similitude
'resemblance' is the definition.
(thesaurus)
'lithium developed inside without hydrogen' is the wordplay.
I cannot quite understand how this works, but
'lithium' could be 'li' (chemical symbol) and 'li' is present in the answer.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for similitude that I've seen before include "Correspondence" , "Nearly identical quality" .)