Small animal of use to a medical person (5)
I believe the answer is:
mouse
'small animal' is the definition.
'mouse' can be an answer for 'animal' (thesaurus). I am unsure of the 'small' bit.
'of use to a medical person' is the wordplay.
'of' becomes 'o''.
'to a' is a charade indicator (letters next to each other) (I've seen this in other clues).
'medical person' becomes 'm' (I am not sure about this - if you are sure you should believe this answer much more).
'o'+'use'='ouse'
'ouse' after 'm' is 'MOUSE'.
Can you help me to learn more?
(Other definitions for mouse that I've seen before include "Rodent (for computing)" , "black eye" , "Timid fellow" , "Small rodent - computer attachment" , "whose movements are captured on screen" .)