Green’s Dictionary of Slang

sharper v.

(Polari)

to look for, to search for.

[UK]R. Milward Man-Eating Typewriter 54: [T]he spiv sycophantically sharpered for a suitable instrument with which to pummel me.

In compounds

sharpering-omi

a detective.

[UK]P. Baker Fabulosa 297/2: sharping-omee, sharpering-omee.
[UK]R. Milward Man-Eating Typewriter n.p.: I remember the slide well: a sharpering-omi with a mogue beard and ogle-fakes terrorising a helpless gypsy in chains.