You just need to ask someone /read guides about solving cryptic crosswords. Once you get used to it, it makes sense, but there can a surprising amount of 'unofficial' knowledge (abbreviations, 'common' crossword answers, etc), or things which are uk-specific and are not straightforward if you're not from the uk.

Some compilers are also easier than others / will make more sense to you (I like brendan, nutmeg, vulcan, and philistine).