Focus attention on removing first lock (5)
I believe the answer is:
tress
'lock' is the definition.
(both can mean a piece of hair)
'focus attention on removing first' is the wordplay.
'focus attention' becomes 'tess' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'removing first' becomes 'r' (tst letter of 'removing').
'tess' going around 'r' is 'TRESS'.
Can you help me to learn more?
(Other definitions for tress that I've seen before include "Obsolete support" , "Curl - lock" , "Long lock or plait of hair" , "Braid of hair" , "Switch" .)