Female, old and obstinate, making concentrated effort (8)
I believe the answer is:
focussed
'concentrated effort' is the definition.
'focussed' can be an answer for 'concentrated' (I've seen this before). I'm not certain of the 'effort' bit.
'female old and obstinate' is the wordplay.
'female' becomes 'f' (common abbreviation).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'and' says to put letters next to each other.
'obstinate' becomes 'cussed' (synonyms).
'f'+'o'+'cussed'='FOCUSSED'
'making' is the link.
Can you help me to learn more?
(Another definition for focussed that I've seen is " Concentrated on as with camera".)