CPC is an auction price, so 'high' means some mix of: competitive keywords (lawyers and locksmiths pay brutal rates), broad targeting pulling you into expensive searches, low relevance scores inflating what you pay versus rivals, or bidding strategies set loose without conversion data.
The fixes mirror the causes: tighten match types and negatives so you only enter auctions you want; raise relevance (ad echoes search, page echoes ad) so Google discounts your clicks; and consider adjacent, longer keywords — 'emergency panel upgrade' costs less than 'electrician' and converts better.
Also check the obvious: search partners and Display expansion settings quietly include cheaper-but-junk inventory or auction types you never chose. Search-only, partners off, is the clean baseline.