Adult more serious about married suitor (7)
I believe the answer is:
admirer
'suitor' is the definition.
(I've seen this before)
'adult more serious about married' is the wordplay.
'adult' becomes 'a' (abbreviation).
'more serious' becomes 'direr' (I can't explain this - if you can you should believe this answer much more).
'about' is an insertion indicator.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'direr' going around 'm' is 'dmirer'.
'a'+'dmirer'='ADMIRER'
Can you help me to learn more?
(Other definitions for admirer that I've seen before include "A young lady's beau - he thinks she's great" , "Supporter or fan" , "Supporter or suitor" , "Married to one who cherishes" , "Married to one who thinks highly of" .)