Dowdy char, possibly, possessing strange power (8)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

RUM (strange) P (power) in FISH (char, possibly); only a pedant would call a woman frumpish, no? Incidentally, I’ve never heard/seen either used to describe a man, though I’ve heard women use it of other women. From the Dutch word meaning ‘wrinkled’ originally.