A feeling that something is true or likely to happen, although you are not certain. (Cambridge Dictionary)
A slight knowledge or suspicion; a hint. (Oxford Dictionaries)
A slight knowledge or suspicion; a hint. clue. (Merriam – Webster)
A slight knowledge or vague notion. (Merriam – Webster)
If you have an inkling of something, you have a vague idea about it. (Collins Dictionary)
The meaning and origin of the expression: Have an inkling. The Phrase Finder.
Have a vague intimation of; have a slight knowledge of.
The detective had an inkling the witness was lying because she kept avoiding his eye contact.