One pound (6)
I believe the answer is:
nicker
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one pound</span>' is the definition.<br/ ><span class="explanation-format__explanation">(nicker can informally mean pound sterling)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nicker that I've seen before include "Pound (slang)" , "PS1 (slang)" , "Sound made by horse" , "One steals" , "One stealing" .)