Determined to give poor Rose an instrument (8)
I believe the answer is:
resolute
'determined to' is the definition.
(similar in meaning)
'give poor rose an instrument' is the wordplay.
'give' says to put letters next to each other.
'poor' indicates an anagram.
'an instrument' becomes 'lute' (lute is a kind of instrument).
'rose' anagrammed gives 'reso'.
'reso' put next to 'lute' is 'RESOLUTE'.
(Other definitions for resolute that I've seen before include "'Firm, unhesitating (8)'" , "Firm-minded" , "Admirably purposeful" , "Showing great determination, fully committed" , "Firm in purpose" .)