In my opinion, yes, it's an adverbial phrase. You settle a debt *by paying to whomever you owe, money* (adverbial descriptor). OR it's "taken in trade" (taken how? 'how' requires adverb); you 'give' him [agree that he will take it, see below] your car. These are ways of settling, ways of 'taking'.
ADDED: I should clarify that the original phrase was about "taking in trade." This is something done by the person holding the debt. In my example above, the person owed takes the debtor's car in trade (I don't mean to say it's forced or coerced or unfair, however). It's a way of settling that might be congenial to both.